Research shows how life might have survived 'snowball Earth'

Oct 11, 2011
Earth

Global glaciation likely put a chill on life on Earth hundreds of millions of years ago, but new research indicates that simple life in the form of photosynthetic algae could have survived in a narrow body of water with characteristics similar to today's Red Sea.

"Under those frigid conditions, there are not a lot of places where you would expect and light to occur in the same area, and you need both of those things for to survive," said Adam Campbell, a University of Washington doctoral student in Earth and space sciences.

A long, narrow body of water such as the Red Sea, about 6.5 times longer than it is wide, would create enough physical resistance to advancing glacial ice that the ice sheet likely could not make it all the way to the end of the sea before conditions cause the ice to turn to vapor. That would leave a small expanse of where the algae could survive.

"The initial results have shown pretty well that these kinds of channels could remain relatively free of thick glacial ice during a 'snowball Earth' event," Campbell said.

He examined the issue using an analytical model that applied basic principles of physics to a simple set of believed to have existed at the time. The results were published Saturday (Oct. 8) in . Co-authors are Edwin Waddington and Stephen Warren, UW professors of Earth and space sciences.

Many scientists believe Earth became a giant snowball two or three times between 800 million and 550 million years ago, with each episode lasting about 10 million years. These all preceded the about 530 million years ago, when rapidly expanded, diversified and became more complex.

But simple photosynthetic plankton turn up in the before and after the "snowball Earth" events, leading scientists to wonder how that could happen if Earth's oceans were completely encased in ice.

Campbell said it is assumed the algae survived these episodes, "unless they re-evolved each time, which creates a whole different problem for evolutionary biology."

He chose the Red Sea as an example because it is formed from a tectonic process called continental rifting, a process known to have existed at the time of the snowball Earth events, and it lies in an arid region between Egypt and the Arabian Peninsula.

Campbell noted that in a event, the open water in such a sea wouldn't have lasted long if it didn't have a way of being replenished – if, for example, the glacial ice acted as a dam and cut off the influx of additional sea water. The open water had to exist on the order of 10 million years for the algae to survive.

"Over 10 million years, you could evaporate the deepest lake in the world," Campbell said. "If you're in a desert, you'd have to have a supply of sea water."

Explore further: NASA's HS3 mission continues with flights over Hurricane Gonzalo

More information: The paper is available at www.agu.org/journals/gl/gl1119/2011GL048846

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d_robison
5 / 5 (7) Oct 11, 2011
Interesting article, global glaciation isn't new find and life survived (obviously), but it does a good job of discussing the all-too-important "How did life survive?" The persistence of life on this planet (and I'm assuming on other planets) is astounding; large object impacts, dramatic climate changes, and extreme volcanic/tectonic activity have not been able to make this planet inhospitable to life.
jsa09
5 / 5 (2) Oct 12, 2011
Since when has snowball Earth meant to mean the Algae would not survive?

Just go to Greenland or look at Glacias in Just about every country that has them. In all cases you will find algae alive and well in the ice.

d_robison
not rated yet Oct 12, 2011
Since when has snowball Earth meant to mean the Algae would not survive?

Just go to Greenland or look at Glacias in Just about every country that has them. In all cases you will find algae alive and well in the ice.



I think the point of the article was to shed light on life in the past and the obstacles it had to overcome in order to be as abundant and resilient as it is today. If scientists just looked at life in its current state and decided its always been this way (no evolution/adaptations, and that it has always been able to survive extreme conditions) then we would be doing ourselves a great disservice.
PinkElephant
not rated yet Oct 13, 2011
shed light on life in the past and the obstacles it had to overcome in order to be as abundant and resilient as it is today
Do you really think that 800 million years ago life was somehow significantly less complex or resilient -- at a single-celled level -- than it is today?

Let's not forget that up to that point, life had already been evolving across all sorts of extreme conditions all over the globe for about 3 billion years or so. Arguably, all the innovations from the Cambrian explosion onward -- including emergence and development of complex multi-cellular organisms -- fade into insignificance compared to all the innovations (at both the molecular/genetic/proteomic and systems/organelle/architectural levels) that occurred *prior* to both the Cambrian explosion and the first known snowball episode.

I concur with jsa09. Not only do certain organisms thrive IN ice, but spores can tolerate being frozen for 10 mil. years, then thaw out and resume life like nothing happened.